<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>demo4</title>
</head>
<style>
    a:link{
     color: deepskyblue;
    }
    a:hover{
        color: crimson;
    }
</style>
<body>
<input type="button" name="12" value="+">
<input type="button" name="12" value="-">
  <script >
      document.getElementById("").onclick=function () {

      }

      setTimeout()
      clearTimeout()
      setInterval()
      clearInterval()
  </script>
<a href="">5456</a>
</body>
</html>